Ink jet printhead cartridges typically use thin film circuitry with electrical contact points to provide power and communication for printing operations. Thin film circuits are used because they can be made very small, which is desired for the ink ejection portion of the printhead. Communications are used to instruct the ink ejection portion of the printhead to fire ink drops with thin film firing resistors of the circuit. These contact points can be very small and should be precisely positioned. As such, in many cases, each contact point is manufactured with close mechanical registration.
However, ink appearance at the printhead near the thin film circuitry during printing can occur under certain circumstances and has been an influential factor affecting printhead reliability. Namely, ink accumulation can penetrate through the circuit traces and cause operating problems. To avoid this, thin film circuits typically have core protective layers that are usually non-permeable. Nevertheless, if a firing resistor in the thin film circuit becomes too hot or becomes damaged, protective layers of the circuit can be breached, thereby exposing the underlying circuitry to corrosive material, such ink.
Resistors in the thin film circuitry are typically arranged in discrete groups known as primitives. Each primitive has a number of resistors. If one resistor in the primitive has a breach of its protective layer, the other resistors in the primitive linked by the same bus could be exposed to the corrosive material. Exposure to corrosive material can adversely affect the printing process by rendering the resistors on the shared power bus inoperable due to electrical opens. Therefore, what is needed is a system and method that solves the above problems.